A protective sleeve placed within the cylinder of a syringe, the sleeve protects a piston and a computer controlled device or human operator pushing the piston from material leaking past a piston assembly. The sleeve has lips or ridges at either end, one that is attached to the piston assembly at the output end of the syringe and a second lip that is attached with a retention plate at the far end of the syringe. The sleeve may have a bellows or accordion configuration that slides along the inner surface of the syringe cylinder without appreciably loading the drive mechanism.
